This audio frequency meter uses 555 IC as a monostable multivibrator (one-shoot trigger). A monostable multivibrator can act as a frequency-to-voltage converter because it produce a fixed pulse width, with the repetition rate/density is proportional to the triggering input frequency. Here is the circuit’s schematic diagram:
For resistor R1, because it set the measurement range, it’s better to use a rotary switch to select different values for different ranges. For the ampere meter, you can use both analog or digital ampere meter. A cheap dual-slope ADC digital meter is suitable because its averaging characteristic, but a fast digital multimeter can also be used although it may show some uncertainty because of their fast sampling.
Possibly Related Articles:
- Phase-Shift Meter for Audio Frequency Signal
Simple phase shift measurement can be done by squaring both the measured and the reference, then compute the difference of the two signals. The accuracy of the circuit shown in... - Frequency To Voltage Converter: Change Your Voltmeter To Frequency Meter
Frequency meter can be used in speed sensor, tachometer, or any measurement of repetitive signals. This frequency to voltage converter (FVC) can be used to turn your analog or digital... - TC9400 Analog Frequency Meter
Any frequency below 100kHz will be converted into an output voltage by TC9400 frequency-to-voltage converter. The TC9400 is linear to the input frequency. The equivalent frequency will be displayed on... - Audio Power Meter: Shows Your Audio Amplifier’s Actual Output Power
Using this circuit, you can measure the actual output power of your amplifier. You can put this circuit in a box as a measurement instrument, or you can integrate it... - Radio Frequency (RF) Watt Meter
For RF (radio frequency) transmitter experiment, watt meter is useful for optimizing the transmitter circuit. A simple RF watt meter circuit is shown in the schematic diagram below. Because circuit... - Audio Decibel Level Meter
This is a circuit of Audio Decibel Level Meter. This circuit uses the SA604 which not only designed as an RF device but also the Received Signal Strength Indicator (RSSI).... - Low Distortion Adjustable Audio frequency Oscillator
Low distortion circuit is very important if we want to measure distortion level of an audio equipment, but this is just one example of low distortion oscillator circuit application. Here... - ESR Meter (Equivalent Series Resistance Meter)
The ESR (Equivalent Series Resistance) of an electrolytic capacitor is normally just a low voltage capacitor (such as a 1000uF, 16V cap), small fraction of an Ohm for a high... - F/V Converter for Frequency Difference Measurement
This is a Frequency Difference Measurement circuit. This circuit consist of two TC9400 that is configured in the F/V mode. So, the TC9400 will convert both frequencies into proportional analog... - VFC110: Single Chip High-Frequency Voltage-to-Frequency Converter (VFC)
Using VFC110 chip, we can build a high frequency voltage-to-frequency converter. The features of this chip include the capability of high frequency operation, disable function, and an on-board precision 5V... - Capacitor ESR Meter
This is schematic diagram of capacitor ESR meter circuit. ESR is equivalent series resistance, and this parameter is used to express the resistance value of any electronic component that basically... - Capacitance Meter
Capacitance meter can be very helpful in identifying old components where its mark has been erased or became unreadable. Such instrument can be quite expensive, but fortunately we can build...
| 
